1. Field of the Invention
The present invention relates to a feature for enhancing the speech database for use in a text-to-speech system.
2. Introduction
Recently, unit selection concatenative synthesis has become the most popular method of performing speech synthesis. Unit Selection differs from older types of synthesis by generally sounding more natural and spontaneous than formant synthesis or diphone-based concatenative synthesis. Unit selection synthesis typically scores higher than other methods in listener ratings of quality. Building a unit selection synthetic voice typically involves recording many hours of speech by a single speaker. Frequently the speaking style is constrained to be somewhat neutral, so that the synthesized voice can be used for general-purpose applications.
Despite its popularity, unit selection synthesis has a number of limitations. One is that once a voice is recorded, the variations of the voice are limited to the variations within the database. While it may be possible to make further recordings of a speaker, this process may not be practical and is also very expensive.